Concerns that terrorists from Africa could try to blow up a U.S.-bound plane have been growing ever since a Nigerian man allegedly tried to bomb a jet over Detroit on December 25. Western officials say one of the biggest terrorism threats comes from Somalia.

If there is a part of the Somali capital that is still considered relatively safe, it is the city's Aden Adde International Airport.

Although insurgents occasionally lob mortars at it, hundreds of African Union peacekeepers from Uganda are deployed in and around the airport to protect it, and to help keep it running.

The presence of armed peacekeepers allows the few commercial planes that fly to Mogadishu, like this Jubba Airways flight from neighboring Kenya, to bring Somalis in and out of the capital and connect them to the rest of the world.

But if the airport acts as a lifeline to the outside for ordinary Somalis, western officials worry that it is also being used by terrorists to travel in and out of Somalia.

Most of Mogadishu and large parts of the country are currently controlled by al-Shabab insurgents, who are believed to be receiving training and support from al-Qaida.

The airport's director, Mohamud Sheik, says the police, A.U. peacekeepers, and employees are vigilant and are doing their best to identify anyone who could pose a security threat. "The security of the airport is tight," he said. "We cannot say it's 100 per cent. You can never say it's 100 percent. But the security has improved. We think it is a very safe environment and we are sure that flights leaving Somalia are secure."

Recent security upgrades include each bag being opened and carefully searched by hand.

But the airport has no X-ray machines, scanners, or metal detectors - all standard items in most airports around the world. Lack of computers means immigration officials at Aden Adde can't check passenger information.

Concrete barriers are also a reminder of the threat that passengers face even before they board a plane. Suicide bombings - unheard of in Somalia until three years ago - are frequent now, especially in areas guarded by peacekeepers.

Scared residents are leaving in droves, some blaming Somalia's western-backed government for the city's mounting security problem.

What's the use of having great airport security if you don't have a government that can provide security and services to the people? This government is weak and it's not functioning, this man says.

The departure lounge fills with more people every day. They leave knowing that in many countries, they won't be receiving a warm welcome anymore.